QUANTITATIVE STUDIES ON THE COMPARATIVE ACTIVITY OF CALCIUM AND CHEMICALLY RELATED IONS ON THE COAGULATION OF BLOOD

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Abstract
By collecting blood in Silicone coated glassware to prevent lysis of platelets and passing it through Amberlite IR-100 to remove Ca, a blood is obtained the composition of which is unaltered except for absence of Ca. The action of Ca and related ions (Sr, Mg and Ba) on the coagulation of blood was quantitatively detd. by adding known concns. of these salts to blood decalcified with Amberlite IR-100. It was found that the min. optimum concn. of Ca is approx. equal to 0.0015 [image], which is the normal level of the blood. Sr is less active and requires a min. concn. of about 0.008 [image]. Mg. is incapable of causing coagulation of decalcified blood unless an excess of active thromboplastin is present. At concns. higher than the optimum Ca and the other bivalent ions exert an inhibitory action on coagulation. By employing an optimum concn. of Ca (0.005 [image]) and an excess of thromboplastin, the inhibitory effect of Sr, Mg and Ba was detd. Ba exerts a marked anticoagulant action due probably to its precipitative effect on proteins. The inhibitory action of Ca, Sr and Mg on coagulation are of the same order of magnitude, but the retarding influence of Ca appears less evident because of its high, coagulative power. It appears that Ca and related ions accelerate or retard cloting purely on the basis of their concn., so that coagulation and prothrombin times are a resultant of a positive or activating and a negative or inhibitory action of these ions. The activating effect takes place directly in the interaction of prothrombin with thromboplastin, while the inhibitory action may perhaps be due to the ability of these ions to stabilize blood proteins, particularly fibrinogen. Extrinsic factors (like the presence of an excess of thromboplastin) may alter the relative domination of one effect over the other. No evidence of a direct antagonism between Ca and related cations on the process of blood clotting was observed.

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